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Fast timing capability in X-ray observation of astrophysical objects is one of the key properties for the ASTRO-H (Hitomi) mission. Absolute timing accuracies of 350 µs or 35 µs are required to achieve nominal scientific goals or to study fast variabilities of specific sources. The satellite carries a GPS receiver to obtain accurate time information, which is distributed from the central onboard computer through the large and complex SpaceWire network. The details on the time system on the hardware and software design are described. In the distribution of the time information, the propagation delays and jitters affect the timing accuracy. Six other items identified within the timing system will also contribute to absolute time error. These error items have been measured and checked on ground to ensure the time error budgets meet the mission requirements. The overall timing performance in combination with hardware performance, software algorithm, and the orbital determination accuracies, etc, under nominal conditions satisfies the mission requirements of 35µs. This work demonstrates key points for space-use instruments in hardware and software designs and calibration measurements for fine timing accuracy on the order of microseconds for midsized satellites using the SpaceWire (IEEE1355) network.

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Infrared sensor system is a major concern for inter-planetary missions in order to investigate the nature and the formation processes of planets and asteroids. Since it takes long time for the communication of inter-planetary probes, automatic and autonomous functions are essential for provisioning observation sequence including the setup procedures of peripheral equipment. Robotics technology which has been adopted on HAYABUSA2 asteroid probe provides functions for setting up onboard equipment, sensor signal calibration, and post signal processing. HAYABUSA2 was launched successfully in 2014 for the exploration of C class near-Earth asteroid 162173 (1999JU3). An optical navigation camera with telephoto lens (ONC-T), a thermal-infrared imager (TIR), and a near infrared spectrometer (NIRS3) have been developed for the observation of geology, thermo-physical properties, and organic or hydrated materials on the asteroid. ONC-T and TIR are used for those scientific purposes as well as assessment of landing site selection and safe descent operation onto the asteroid surface for sample acquisition. NIRS3 is used to characterize the mineralogy of the asteroid surface by observing the 3-micron band, where the particular diagnostic absorption features due to hydrated minerals appear.Modifications were required in order to apply robotics technology for the probe due to the difference of operation on satellites from robot operation environment. The major difference is time line consideration, because the standardized robotics operation software development system is based on event driven framework. The consistency between the framework of time line and event driven scheme was established for the automatic and autonomous operation for HAYABUSA2.